Monolithic rail platform and bolt assemblies for a firearm

ABSTRACT

A firearm assembly for a firearm can include a monolithic rail platform with a handguard portion and an upper receiver portion. The barrel of the firearm can be positioned through the bandguard portion and secured with the upper receiver portion. A firearm assembly can also include a bolt assembly with a bolt carrier having minimized land area and a forward end sized for receipt in the barrel extension at the rearward end of the barrel.

BACKGROUND

The use of automatic and semi-automatic rifles is commonly known to beprevalent in the military. Such weapons typically employ an upperreceiver and bolt action operating system. One standard weapon for theU.S. Military is the M-16 rifle. Semi-automatic rifles such as the AR15type are used in the civilian sector. Such rifles can be further adaptedfor single shot action. The structure and mechanisms of semi-automaticand automatic rifles have been the subject of much refinement andvariation over the years.

While there have been advances in the designs of prior art rifles, thereremains room for additional improvements. The present invention isdirected toward providing various improvements to semi-automatic andautomatic rifles.

SUMMARY

The present invention is directed to monolithic rail plate platforms andbolt assemblies for rifles.

According to one aspect, there is provided a monolithic rail platformthat includes a handguard portion and an upper receiver portionintegrally formed with one another as a single component.

According to another aspect, there is provided an improved bolt carrierfor a semi-automatic or automatic rifle.

According to a further aspect, there is provided an improved operatingsystem for a semi-automatic or automatic rifle.

According to yet another aspect, there is provided an improved rifleassembly for attachment of peripheral components thereto.

These and other aspects will also be apparent from the followingdescription of the illustrated embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of an upper portion of a firearm.

FIG. 2 is a top view of an monolithic rail platform comprising the upperportion of FIG. 1.

FIG. 3 is a side view of the monolithic rail platform of FIG. 2.

FIG. 4 is a bottom view of the monolithic rail platform of FIG. 2.

FIG. 5 is an inverted side view of the monolithic rail platform of FIG.2 looking at the side opposite the side shown in FIG. 3.

FIG. 6 is a right end view of the monolithic rail platform of FIG. 2.

FIG. 7 is a left end view of the monolithic rail platform of FIG. 2.

FIG. 8 is a top view of a bolt carrier comprising a portion of the upperportion of FIG. 1.

FIG. 9 is a side view of the bolt carrier of FIG. 8.

FIG. 10 is a right end view of the bolt carrier of FIG. 8.

FIG. 11 is a bottom view of the bolt carrier of FIG. 8.

FIG. 12 is a left end view of the bolt carrier of FIG. 8 as oriented inFIG. 11.

FIG. 13 is a section view through line 13-13 of FIG. 12.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any such alterations and furthermodifications in the illustrated device, and any such furtherapplications of the principles of the invention as illustrated hereinare contemplated as would normally occur to one skilled in the art towhich the invention relates.

An assembly 20 for an upper portion of a firearm is shown in FIG. 1 inan exploded view. The lower receiver assembly, butt stock and magazineare not shown in FIG. 1, it being understood that the lower receiver,butt stock and magazine can be provided in any configuration suitablefor an automatic M16/AR15 type rifle or other type or calibersemi-automatic or automatic rifle. Assembly 20 includes a barrelassembly 21 that includes a barrel 22 having a gas block 24 attachableto a forward end thereof. A gas tube 26 extends rearwardly from gasblock 24 to the weapon operating system. A barrel extension 28 isattachable to the rearward end of barrel 22 adjacent cartridge chamber30. Barrel extension 28 is configured to interlock with the bolt, suchas bolt 102. Further details regarding one embodiment bolt 102 andbarrel extension 28 are provided in U.S. Pat. No. 6,182,389, which isincorporated herein by reference in its entirety. Assembly 20 furtherincludes an monolithic rail platform 50 that includes a handguardportion 52 integrally formed with an upper receiver portion 70.

Referring now further to FIGS. 2-7, when assembly 20 is assembled, abolt carrier 120 housing bolt 102 is positioned in and movably receivedalong the longitudinal axis of bore 70 a of upper receiver portion 70,and barrel assembly 21 is positioned in bore 52 a of handguard portion52. Barrel assembly 21 is secured to monolithic rail platform 50 withfasteners 54 a, 54 b and clamping nuts 55 a, 55 b. Fasteners 54 a, 54 bextend through respective ones of the holes 56 a, 56 b throughmonolithic rail platform 50. Clamping nuts 55 a, 55 b are coupled to thethreaded ends of fasteners 54 a, 54 b to clamp monolithic rail platform50 around enlarged portion 22 a of barrel 22 at the forward end of upperreceiver portion 70. It is further contemplated that fastener 54 b canact as a locating and retaining pin by interacting with enlarged portion28 a of barrel extension 28 to ensure that barrel 22 is properlypositioned and located in monolithic rail platform 50. For example,fastener 54 b can be received in a recess formed in an outer surface ofenlarged portion 28 a of barrel extension 28 when barrel 22 is at theproper locating in bore 52 a of handguard portion 52. Fastener 54 b canresist any forward movement of barrel 22 and barrel extension 28 thatmight be created b contact of the bolt carrier therewith.

Handguard portion 52 includes a number of rails 58 extending therealongseparated by recesses 60 therebetween. Rails 58 include transversegrooves 59 formed therein to facilitate gripping of handguard portion52. A number of threaded holes 63 are spaced along each rail 58 to allowattachment of peripheral devices, such as a grenade launcher, site,sling and/or scope, for example. Recesses 60 each include a number ofholes 62 formed therein along handguard portion 52 to allow air flow andheat from barrel 22 to vent therethrough.

Handguard portion 52 further includes a rearward extension 58 a for theupper rail 58 that extends along upper receiver portion 70. The rearwardextension 58 a includes a passage 64 formed therethrough thatcommunicates gas tube 26 to provide a path for delivering gas to theoperating system of the rifle. The forward end 52 b of handguard portion52 includes a triangular shaped opening 52 c adapted to receive theupper extension 24 a of gas block 24. Gas tube 26 is coupled to upperextension 24 a of gas block 24.

Upper receiver portion 70 includes a forward end 70 b integrally formedwith handguard portion 52 and a rearward end 70 c. Forward end 70 b cancomprise a clamping portion having clamping members 70 e, 70 fpositioned on opposite sides of slot 70 d to facilitate clamping ofupper receiver portion 70 about barrel 22. A cut-out 65 is formed inforward end 70 b to reduce weight. Upper receiver portion 70 furtherincludes a forward lug 72 a and a rearward lug 72 b extending downwardlyfrom a bottom side thereof. The lower receiver assembly (not shown) isattachable to lugs 72 a, 72 b. Upper receiver portion 70 furtherincludes ejection port opening 74 and ejection port cover receptacles 76a, 76 b on opposite sides thereof. Ejection port receptacles 76 a, 76 breceive pins that pivotally couple an ejection port cover (not shown)over opening 74. A deflector 78 extends outwardly from upper receiverportion 70 adjacent the rearward end of ejection portion opening 74 todeflect ejected cartridges away from the shooter. Upper receiver portion70 further includes a forward assist port 80 that receives a forwardassist mechanism (not shown) to assist in positioning the bolt carrierassembly 100 in its forward battery position in upper receiver portion70 if needed.

Opposite ejection port receptacle 74 there is a lip of material 84 tosupport a cam pin cut-out in the upper receiver portion 70. Upperreceiver portion 70 further includes in the bottom side thereof a firstopening 82 a along a rearward portion thereof for receiving the triggerassembly of the lower receiver assembly. Upper receiver portion 70 alsoincludes a second opening 82 b along a forward portion thereofcommunicating with the magazine receptacle of the lower receiverassembly for receiving cartridges therethrough from the magazine of therifle. Second opening 82 b is wider than first opening 82 a and firstand second openings 82 a, 82 b are in communication with one anotheralong the bottom portion of upper receiver portion 70. The rearward end70 c of upper receiver portion 70 is positionable adjacent the lowerreceiver extension assembly and buttstock assembly of the lower receiverassembly when the rifle is assembled.

With barrel 22 secured to the coupling portion at forward end 70 b ofupper receiver portion 70, handguard portion 52 can extend around barrel22, but need not be supported by, or in contact with, or coupled tobarrel 22. Accordingly, barrel 22 can float in bore 52 a of handguardportion 52. Monolithic rail platform 50 allows the hoop strength ofhandguard portion 52 to be maximized since, in one embodiment, it isprovided as a single continuous ring extending along barrel 22. Theintegral unitary construction of upper receiver portion 70 and handguardportion 52 provide a stronger, reliable rifle assembly since there arefewer parts that require assembly. Peripheral devices, such as scopemounts, sites, slings, and grenade launchers, for example, that aremounted on handguard portion 52 do not apply load on or influence barrel22, improving rifle accuracy. Rather, such loads and other influencescreated by these peripherals are transmitted from handguard portion 52to upper receiver portion 70. Furthermore, in one embodiment, anythreaded connection between barrel 22 and upper receiver portion 70 iseliminated, allowing rapid attachment and detachment of barrel 22 viafasteners 54 a, 54 b. The integral upper receiver and handguard portionsand means of attaching the barrel allow for rapid assembly anddisassembly of rifle components, which can be critical in the field.

Referring now to FIGS. 8-13, further details regarding bolt carrier 120of bolt assembly 100 will be provided. Bolt carrier 120 includes aforward end 120 a and an opposite rearward end 120 b. Forward end 120 ais oriented toward barrel 22 when bolt carrier 120 is positioned inupper receiver portion 70. A passage 120 d extends between forward end120 a and rearward end 120 b along a longitudinal axis of bolt carrier120. Passage 120 d has a minimum diameter portion 120 c sized to receivethe reduced diameter end portion 102 a of bolt 102 when positionedtherein. Passage 120 d further includes a bolt receiving portion 120 eextending forwardly from minimum diameter portion 120 c to forward end120 a to receive the remaining portion of bolt 102. Bolt 102 is mountedin bolt carrier 120 for axial sliding movement in forward portion 120 e.Bolt 102 includes a cartridge extractor 104 pivotally coupled thereto,and includes lugs 106 at the forward end thereof that releasablyinterlock with barrel extension 28. A firing pin (not shown) extendsthrough a central bore through bolt 102. A cam slot 124 is formedadjacent forward end 120 a which receives a cam member therethrough forcontacting bolt 102 to rotate it as it moves rearwardly and forwardlyfor engagement with barrel extension 28.

Bolt carrier 120 includes a slot 134 therethrough that receives thehammer from the lower receiver assembly to strike the firing pin in bolt102. Bolt carrier 120 further includes gas key mounting holes 136 formedin an upper mounting surface 131 of bolt carrier 120. Gas key mountingholes 136 communicate with passage 120 d. A gas port 138 is furtherprovided in mounting surface 131 and includes ports extending therefromin communication with passage 120 d. One side of bolt carrier 120 isprovided with forward assist notches 144 which are engageable by aforward assist mechanism (not shown) in forward assist port 80 of upperreceiver portion 70. Bolt carrier 120 further includes a door opener 122that is recessed in the body of bolt carrier 120 to provide room for thedoor latch to close. Bolt carrier 120 includes a charging handle contactportion 146 adjacent forward end 120 a.

Rearward end portion 130 includes a groove 132 cut therein along thelongitudinal axis of bolt carrier 120 to maintain alignment of boltcarrier 120 as it axially reciprocates in upper receiver portion 70.Bolt carrier 120 further includes forward lands 126 a, 126 b, 126 c, and126 d extending along the forward half of bolt carrier 120. Lands 126 a,126 b extend along the upper portion of bolt carrier 120 along mountingsurface 131 and terminate at contact portion 146. Lands 126 c and 126 dextend along the bottom portion of bolt carrier 120 and terminate atforward end 120 a. The lands 126 a, 126 b 126 c, 126 d contact the innerwall of bore 70 a of upper receiver portion 70 to maintain alignment ofbolt carrier 120 centrally therein and also in alignment with thecenterline of barrel 22. The land area along bolt carrier 120 and alsoalong forward end portion 148 is minimized by reducing the land area inthe range from one-half to one twenty-fifth of that of prior art boltcarriers.

The portion of bolt carrier 120 along which each of the lands 126 a, 126b, 126 c, 126 d extends has a surface area, and lands 126 a, 126 b, 126c, 126 d occupy a portion of that surface area. In one embodiment, asection of bolt carrier 120 including lands 126 a, 126 b, 126 c, 126 doccupies a surface area that ranges from 1% to 12% of the surface areaof the occupied portion of the bolt carrier 120. In another embodiment,lands 126 a, 126 b, 126 c, 126 d occupy a surface area that ranges from1% to 8% of the surface area of the occupied portion of the boltcarrier. In another embodiment, lands 126 a, 126 b, 126 c, 126 d occupya surface area that ranges from 1% to 4% of the surface area of theoccupied portion of the bolt carrier.

By minimizing the land area, the contact surface area between bolt 120and the wall of bore 70 a of upper receiver portion 70. This allowsgreater ease of movement of bolt carrier 120 in upper receiver portion70. The reduced contact area also provides greater clearance betweenbolt carrier 120 and any particles in bore 70 a of upper receiverportion 70, allowing bolt carrier 120 to deposit such particles anddebris in the recessed areas between the lands to provide aself-cleaning action that reduces malfunction in harsh environments andwith prolonged usage.

The protrusion 125 at the forward end of bolt carrier 120 is sized forreceipt in the rearwardly facing opening of barrel extension 28.Protrusion 125 is positioned radially inwardly from the outer perimeterof forward end 120 a, and includes a sloped or chamfered outer surfacethat extends from a first diameter at rearward end 125 b adjacentforward end 120 a to a reduced diameter forward face 125 b at theforward end of protrusion 125. Bore 120 d extends through protrusion125. Protrusion 125 allows bolt carrier 120 to be positioned moreforwardly in upper receiver portion 70 as compared to a bolt carrierhaving the same overall length without protrusion 125. By positioningbolt carrier 120 more forwardly in upper receiver portion 70, the timerequired to move bolt carrier 120 rearwardly to turn bolt 102 isincreased. Protrusion 125 thus increases the stroke length for boltcarrier 120 in upper receiver portion 70. The additional stroke lengthprovided by protrusion 125 increases the dwell time of bolt 102 inbarrel extension 28, allowing residual gas pressure in barrel 22 moretime to vent before bolt 102 unlocks with barrel extension 28.

In one embodiment, protrusion 125 is sized to extend forwardly adistance of one hundred thousandths of an inch to increase the dwelltime of bolt 102 by up to two times that provided in bolt carrierswithout protrusion 125. It is contemplated that other embodiments mayprovide other lengths and/or other dwell times associated withprotrusion 125. The reduced gas pressure in the blowback operationreduces the load exerted on extractor 104 during the extraction cycle,improving system operation in the extraction and ejection cycles for thespent cartridge. For example, by venting additional gas pressure beforeextraction, expansion of the spent cartridge casing is reducedfacilitating extraction and reducing the extraction loading. The loadand forces exerted on bolt 102, barrel extension 28, and upper receiverportion 70 are reduced. Thus, rather than having excess energy from thegas pressure consumed in the recoil cycle, more energy is directed foruse in the counter recoil cycle and feeding and chambering ofcartridges. The increased stroke length thus increases overall systemoperability, reliability and the life of the firearm. Operatingperformance with attachments that affect the gas operation of the rifleare also improved. For example, silencers accumulate gas to muffle thenoise. The additional dwell time allows more gas to vent to the breech,reducing load on the barrel and providing longer barrel life whensilencers are employed.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character. All changes andmodifications that come within the spirit of the invention are desiredto be protected.

1. A monolithic rail platform for a firearm, comprising: a handguardportion adapted to receive at least a portion of a barrel assembly ofthe firearm therein; and an upper receiver portion extending rearwardlyfrom and integrally formed with said handguard portion, said upperreceiver portion adapted to receive a bolt carrier therein.
 2. Theplatform of claim 1, wherein said upper receiver portion includes a boreextending along a longitudinal axis thereof, said bolt carrier beingmovably received in said bore of said upper receiver portion along saidlongitudinal axis.
 3. The platform of claim 1, further comprising acoupling portion at a forward end of said upper receiver portion andintegral with said handguard portion, said coupling portion adapted toreleasably clamp a rearward end of said barrel assembly extendingthrough said handguard portion to said upper receiver portion.
 4. Theplatform of claim 3, wherein said upper receiver portion includes alongitudinal axis and said coupling portion includes a slot extending inthe direction of said longitudinal axis separating said coupling portioninto first and second clamping portions positioned on respective sidesof said slot.
 5. The platform of claim 4, further comprising at leastone fastener positionable through said coupling portion transversely tosaid longitudinal axis, said at least one fastener operable to bringsaid clamping portions toward one another to clamp said barrel assemblyin said coupling portion.
 6. The platform of claim 5, further comprisinga pair of fasteners positionable through said coupling portiontransversely to said longitudinal axis, one of said pair of fastenerspositioned against a an enlarged portion of said barrel assembly toresist forward movement of said barrel assembly.
 7. The platform ofclaim 1, wherein said handguard portion includes a number of railsextending therealong separated by recessed portions therebetween.
 8. Theplatform of claim 7, wherein said number of rails includes an upper railextending rearwardly along said upper receiver portion.
 9. The platformof claim 8, wherein said upper rail includes a passage formed therealongfor delivering gas from a forward end of said barrel.
 10. The platformof claim 1, wherein said handguard portion extends along said barrelassembly to a position adjacent a forward end of said barrel assembly.11. The platform of claim 1, wherein said upper receiver portionincludes a first opening along a bottom side thereof adapted to receivea trigger assembly and a second opening along said bottom side thereofin communication with and forming a forward extension of said firstopening, said second opening adapted to receive a magazine therein. 12.The platform of claim 1, wherein said barrel assembly is attachable tosaid upper receiver portion and extends through said handguard portionin a floating relationship therewith.
 13. The platform of claim 1,wherein the monolithic rail platform comprises a portion of a boltaction rifle.
 14. The platform of claim 1, wherein: said barrel assemblyincludes a barrel extension at a rearward end thereof; said upperreceiver portion includes a longitudinal bore extending therethrough incommunication with said barrel extension; and said bolt carrierincluding a protrusion at a forward end thereof, said protrusion beingsized for receipt in said barrel extension thereby increasing a strokelength of said bolt carrier in said longitudinal bore of upper receiverportion.
 15. A firearm assembly, comprising: a handguard portion; abarrel assembly extending through said handguard portion, said barrelassembly including a barrel extension at a rearward end thereof; anupper receiver portion extending from a rearward end of said handguardportion, said upper receiver portion including a longitudinal boreextending therethrough in communication with said barrel extension; anda bolt assembly movably positioned in said longitudinal bore, said boltassembly including a bolt carrier having a protrusion at a forward endthereof, said protrusion being sized for receipt in said barrelextension thereby increasing a stroke length of said bolt carrier insaid longitudinal bore of said upper receiver portion.
 16. The platformof claim 15, wherein said handguard portion is integrally formed withsaid upper receiver portion.
 17. The assembly of claim 15, furthercomprising a coupling portion at a forward end of said upper receiverportion integral with said handguard portion, said coupling portionadapted to releasably clamp a rearward end of said barrel assemblyextending through said handguard portion to said upper receiver portion.18. The assembly of claim 17, wherein said upper receiver portionincludes a longitudinal axis and said coupling portion includes a slotextending in the direction of said longitudinal axis separating saidcoupling portion into first and second clamping portions positioned onrespective sides of said slot.
 19. The assembly of claim 18, furthercomprising at least one fastener positionable through said couplingportion transversely to said longitudinal axis, said at least onefastener operable to bring said clamping portions toward one another toclamp said barrel assembly in said coupling portion.
 20. The assembly ofclaim 15, wherein said handguard portion includes a number of railsextending therealong separated by recessed portions therebetween. 21.The assembly of claim 20, wherein said number of rails includes an upperrail extending rearwardly along said upper receiver portion.
 22. Theassembly of claim 15, wherein said handguard portion extends along saidbarrel assembly to a position adjacent a forward end of said barrelassembly.
 23. The assembly of claim 15, wherein said barrel assembly isattachable to said upper receiver portion and said handguard portionextends around and is separated from said barrel assembly.
 24. Theassembly of claim 15, wherein said bolt carrier includes a forward endportion and a rearward end portion, said forward end portion including anumber of lands extending therealong and spaced thereabout forcontacting said upper receiver portion in said bore, said number oflands occupying from about 1% to about 12% of a surface area of saidforward end portion along which said number lands extend.
 25. Theassembly of claim 15, wherein said protrusion extends into said barrelextension for a distance of one hundred thousandths of an inch when saidbolt carrier is positioned completely forwardly in said upper receiverportion.
 26. A firearm assembly, comprising: a handguard portion; abarrel assembly extending through said handguard portion; an upperreceiver portion extending from a rearward end of said handguardportion, said upper receiver portion including a longitudinal boreextending therethrough in communication with said barrel extension; anda bolt assembly movably positioned in said longitudinal bore, said boltassembly including a bolt carrier including a forward end portion and arearward end portion, said forward end portion including a number oflands extending therealong and spaced thereabout, said number of landsoccupying from about 1% to about 12% of a surface area of said forwardend portion along which said number of lands extend.
 27. The assembly ofclaim 26, wherein said number of lands occupy from about 1% to about 8%of said surface area of said forward end portion.
 28. The assembly ofclaim 26, wherein said number of lands occupy from about 1% to about 4%of said surface area of said forward end portion.
 29. The assembly ofclaim 26, wherein said number of lands occupy about 4% of said surfacearea of said forward end portion.
 30. The assembly of claim 26, whereinsaid barrel assembly includes a barrel extension at a rearward endthereof.
 31. The assembly of claim 26, wherein said bolt carrierincludes a protrusion at a forward end thereof, said protrusion beingsized for receipt in said barrel extension thereby increasing a strokelength of said bolt carrier in said longitudinal bore of said upperreceiver portion.
 32. The assembly of claim 26, wherein said handguardportion and said upper receiver portion are formed as an integral unit.33. The assembly of claim 26, further comprising a coupling portion at aforward end of said upper receiver portion and integral with saidhandguard portion, said coupling portion adapted to releasably clamp arearward end of said barrel assembly extending through said handguardportion to said upper receiver portion.
 34. The assembly of claim 33,wherein said upper receiver portion includes a longitudinal axis andsaid coupling portion includes a slot extending in the direction of saidlongitudinal axis separating said coupling portion into first and secondclamping portions positioned on respective sides of said slot.
 35. Theassembly of claim 26, wherein said handguard portion extends along saidbarrel assembly to a position adjacent a forward end of said barrelassembly.
 36. The assembly of claim 26, wherein said barrel assembly isattachable to said upper receiver portion and extends through saidhandguard portion in a floating relationship therewith.